code: def load_dataset(self, suffix, is_sparse=False):
      filename = str(self.path(suffix))
      if is_sparse:
          X, Y = load_svmlight_file(
              filename, dtype=np.float64, zero_based=True
          )
          return X, Y, filename
      else:
          mat = np.loadtxt(filename, dtype=np.float64)
          return mat[:, 1:], mat[:, 0], filename
  
file_path: LightGBM/tests/python_package_test/test_consistency.py
imports: from pathlib import Path
  import numpy
  from sklearn.datasets import load_svmlight_file
  import lightgbm
label_desc: Use image node_id 2 for calling the FileLoader obj's underlying member method code with example usage: obj.load_dataset(suffix, is_sparse) and returns: X,  Y,  filename, mat,  mat,  filename